Bone mineralization changes, particularly losses as in osteoporosis, are characteristic of aging. They are reflected by changes in mechanical and elastic propertis of bone which can be studied by physical methods including ultrasonics. The Lee-Davidson hypothesis by taking into account the stereochemical structure of collagen, asserts that the the matrix stiffens due to the mineralization process. It is intended to continue to investigate the relationship between sonic velocity and other bone properties using a consistent protocol to permit intercomparison of data. Parameters will include density; mineral, water and organic components; age, sex, species and disease; influence of agents like ethanol and glycerin. Data will be gotten from intact bone specimens and from fused composites of KBr and bone powder. Elastic properties and dimensional changes will be correlated with parameters noted above. Histological examination, SEM mapping and ultrasonic microscopy will aid in relating bone anisotropy to orientation of collagen fibers and osteons. Longitudinal and shear wave propagation will be studied in a uniform test procedure over a wide spanning data base. Emphasis wll be given to diseases affecting collagen cross-linking. The information should add insight and understanding to the fundamental processes controlling the elastic properties of bone at the molecular and ultrastructural level. It will contribute to the knowledge of the characteristics of bone as affected by age and disease and posibly to the treatment of osteoporosis, osteodystrophy and osteogenesis imperfecta.